public abstract class SistemaLeilaoAbstract{
	private IUsuario usuario;
	private ILeilao leilao;
	private ICorreio correio;
	
	public final void iniciarLeilao(ILeilao leilao){
		this.leilao = leilao;
	}
	
	public abstract void darLance(double valor) throws Exception;
	public abstract boolean finalizarLeilao(IUsuario usuario);
}